1. Field of the Invention
This invention generally relates to a cleaning device for cleaning the imaging surface by removing residual toner particles therefrom to prepare the imaging surface for the next imaging cycle, and, in particular, to a magnetic cleaning device for use in an electrostatographic copying machine and the like, which uses magnetic toner particles for development of an electrostatic latent image.
2. Description of the Prior Art
In a typical electrostatographic copying machine such as an electrophotographic or electrostatic copying machine, a toner image, which is a copy of an original image, is formed on the imaging surface and the thus formed toner image is transferred to a transfer medium such as plain paper, followed by cleaning of the imaging surface by removing the nontransferred toner particles remaining on the imaging surface after image transfer thereby preparing the imaging surface ready for the next cycle of operation. A fur brush cleaning device has been commonly used to carry out such a cleaning operation and the typical prior art fur brush cleaning device is comprised of a sleeve on the outer peripheral surface of which is fixedly provided fur brush. The sleeve is driven to rotate such that the fur brush may brush or scrub the imaging surface thereby removing the residual toner particles therefrom. As a result, the toner particles removed from the imaging surface are held by the fur brush and they are transported along the rotation of the sleeve. A knock-off bar is usually provided in scrubbing contact with the fur brush, so that the toner particles now held by the fur brush are knocked off to become airborne. Then these toner particles drifting in the air are brought into a collection chamber as guided by an air flow created by a suction device.
In such a fur brush cleaning device, when the fur brush is made of a material which is charged due to friction with the toner particles and the imaging surface to the polarity opposite to that of the charges acquired by the toner particles, the toner particles may be easily caused to adhere to the fur brush thereby allowing to obtain a high removing efficiency. In such a case, however, since the toner particles rather strongly adhere to the fur brush, the knocking off operation becomes deteriorated, and, therefore, the overall cleaning efficiency stays relatively low. On the other hand, in the case where the fur brush is formed by a material which is electrically conductive or semiconductive, the fur brush is either difficult to be charged or hardly charged due to friction, so that the toner particles may be easily removed from the fur brush. In this case, however, the toner removing operation from the imaging surface is rather low in efficiency.
Under the circumstances, there has been a need for the advent of a new cleaning device.